Gas exchange and cell membranes: Edexcel International A Level Biology questions

Every Edexcel International A Level Biology exam question on Gas exchange and cell membranes (specification points 2.1–2.3), 2019–2025, with its mark scheme and examiner’s report.

All 91 questions on Gas exchange and cell membranes, as a list

June 2025, AS Unit 1, Q4(a) (3 marks): The gas exchange surfaces of a frog change as a tadpole develops into an adult frog. The graph shows some of these changes. 100 80 lungs Percentage of 60 oxygen
June 2025, AS Unit 1, Q4(c) (6 marks): The diagram shows the distribution of blood flowing through the circulatory system of a frog. The percentages of blood flowing through the parts of the circulat
June 2025, AS Unit 1, Q6(a)(i) (1 mark): Which structure prevents large polar (hydrophilic) molecules from diffusing through the membrane? (1) A Q B R C T D V
June 2025, AS Unit 1, Q6(a)(ii) (1 mark): Which structure allows ions to diffuse through the membrane? (1) A P B S C T D U
June 2025, AS Unit 1, Q6(a)(iii) (1 mark): Which structure allows the membrane to be fluid? (1) A P B Q C S D U
June 2025, AS Unit 1, Q6(b) (1 mark): The diagram shows a cholesterol molecule. polar (hydrophilic) region non-polar (hydrophobic) region Which diagram shows the correct position of a cholesterol mo
June 2025, AS Unit 1, Q6(c) (3 marks): The graph shows the effect of temperature and cholesterol on membrane fluidity. without cholesterol with cholesterol Membrane ﬂuidity Temperature Describe the e
June 2025, AS Unit 1, Q6(d)(i) (1 mark): Calculate the ratio of protein : lipid in membrane A. Give your answer to 2 decimal places. (1) Answer : 1
June 2025, AS Unit 1, Q6(d)(ii) (3 marks): Compare and contrast the composition of these three membranes. (3)
June 2025, AS Unit 3, Q2(a)(i) (5 marks): Justify each step of a method that could be used to obtain the results shown in the graph. (5)
June 2025, AS Unit 3, Q2(b)(i) (2 marks): Complete the key by naming the molecules. (2)
June 2025, AS Unit 3, Q2(b)(ii) (1 mark): Complete diagram A by labelling the inside and outside of the cell. (1)
June 2025, AS Unit 3, Q2(b)(iii) (1 mark): Draw an arrow next to diagram A to show the net movement of betalain during the experiment. (1)
January 2025, AS Unit 1, Q7(a) (2 marks): Overton suggested that some types of solute could cross the lipid membrane, whereas other types of solute could not. Explain the difference between these two ty
January 2025, AS Unit 1, Q7(b) (2 marks): Langmuir’s model was a single layer of phospholipids. Explain why the phospholipids in a cell membrane cannot be arranged in a single layer. (2)
January 2025, AS Unit 1, Q7(c) (2 marks): Gorter and Grendel suggested that there were various types of phospholipid but they were all arranged in a bilayer. Give two ways in which phospholipids can be
January 2025, AS Unit 1, Q7(d) (2 marks): The Davson and Danielli model was the first to include proteins. Explain why some membrane proteins would not be able to carry out their transport functions if
January 2025, AS Unit 1, Q7(e) (2 marks): Robertson implied that there was no space between the phospholipid layers and that the thickness of the membrane could be measured. The photograph shows part of
January 2025, AS Unit 1, Q7(f) (2 marks): In 1972, Singer and Nicolson proposed the fluid mosaic model of the cell membrane. Explain why their model has been given this name. (2)
October 2024, AS Unit 1, Q1(a) (1 mark): An amoeba changes shape by pushing cytoplasm against the cell membrane, forming long thin projections. State the property of the cell membrane that enables the
October 2024, AS Unit 1, Q1(b)(i) (1 mark): The amoeba can be roughly spherical, as shown in Shape 1. Which is the surface area of the amoeba in this shape? Use the formula: surface area of a sphere = 4πr
October 2024, AS Unit 1, Q1(b)(ii) (1 mark): The mass of the amoeba stays the same when it changes from Shape 1 to Shape 2. Which row of the table shows what happens to the surface area and volume of this
October 2024, AS Unit 1, Q1(b)(iii) (2 marks): Explain why an amoeba can rely on diffusion to supply the oxygen it needs. (2)
October 2024, AS Unit 3, Q3(c)(i) (2 marks): Suggest two factors that may affect the rate of diffusion of the antimicrobial molecules. (2) 1 2
June 2024, AS Unit 1, Q4(b)(i) (1 mark): Name two other factors that affect the rate of diffusion. (1) 1 2
June 2024, AS Unit 1, Q4(b)(ii) (1 mark): Name the law of diffusion that can be used to calculate the rate of diffusion. (1)
June 2024, AS Unit 1, Q4(c)(i) (2 marks): Complete the table to show the missing values. (2)
January 2024, AS Unit 1, Q6(a) (1 mark): Name the current model for the structure of the cell membrane. (1)
January 2024, AS Unit 1, Q6(b) (3 marks): Describe the arrangement of phospholipids in the cell membrane in this model. (3)
January 2024, AS Unit 1, Q6(c)(i) (3 marks): Lipid nanoparticles are very small. Calculate the diameter of a lipid nanoparticle with a volume of 0.108 µm3. Use the formula = 4 3 V r 3 Use π = 3.0 (3) Ans
January 2024, AS Unit 1, Q6(c)(iii) (3 marks): Explain the arrangements of phospholipids in this lipid nanoparticle that carries mRNA to tissues in the body. (3)
January 2024, AS Unit 3, Q2(a) (2 marks): Name three types of molecule present in structure A. (2) 1 2 3
January 2024, AS Unit 3, Q2(b) (3 marks): Some of the evidence for the structure of cell membranes comes from studies of permeability. The solubility of substances A to E in olive oil was determined. Th
January 2024, AS Unit 3, Q2(c)(i) (3 marks): Explain the results of this investigation. (3)
January 2024, AS Unit 3, Q2(c)(ii) (5 marks): Describe a procedure that could have been used to obtain the results shown in this graph. (5)
October 2023, Unit 4, Q1(d)(i) (1 mark): How many of the structures labelled P, T, U and W are made of phospholipids? (1) A 1 B 2 C 3 D 4
October 2023, Unit 4, Q1(d)(ii) (1 mark): Which describes a phospholipid? (1) A glycerol attached to two fatty acids and one phosphate group B glycerol attached to two fatty acids and two phosphate grou
June 2023, AS Unit 1, Q4(a)(i) (1 mark): Which is the magnification of this drawing? (1) A 3.75 × 10–2 B 3.75 × 10–1 C 2.67 × 100 D 2.67 × 101
June 2023, AS Unit 1, Q4(a)(ii) (1 mark): Which is the surface area, in mm2, of this hydra? Use the formula: surface area = 2πrl (1) A 0.9 π B 1.8 π C 3.6 π D 5.4 π
June 2023, AS Unit 1, Q4(a)(iii) (2 marks): Another hydra has a surface area of 2.3 π mm2, a body length of 1.8 mm and a diameter of 1.2 mm. Calculate the surface area to volume ratio of this hydra. Use t
June 2023, AS Unit 1, Q4(b) (3 marks): A hydra has a hollow body that is made up of two layers of cells. Explain how a hydra is adapted for gas exchange. (3)
January 2023, AS Unit 1, Q6(a)(i) (1 mark): Which describes a phospholipid? (1) A hydrophilic fatty acid head and hydrophobic phosphate tails B hydrophilic phosphate head and hydrophobic fatty acid tails
January 2023, AS Unit 1, Q6(a)(ii) (4 marks): Compare and contrast the structure of the model shown in the diagram with that of the fluid mosaic model of membrane structure. (4)
January 2023, AS Unit 1, Q6(b)(i) (2 marks): Suggest how damage to the cell membrane could result in cell death. (2)
January 2023, AS Unit 1, Q6(b)(ii) (2 marks): Cells can repair damage to the cell membrane. This involves fusion of parts of the membrane around the edge of the damage. Explain why parts of the membrane are
January 2023, AS Unit 1, Q6(b)(iii) (2 marks): Once the membrane has fused together, other processes are needed to complete the repair of the membrane. Suggest what else the cell needs to do to complete this
January 2023, AS Unit 1, Q7(b) (3 marks): Explain why large lungs and a large heart would help a yak to survive at high altitudes. (3)
January 2023, AS Unit 1, Q7(c)(ii) (2 marks): The diagram gives some information about two spheres, sphere A and sphere B. Sphere A Sphere B 8 mm 16 mm • sphere A has a surface area : volume ratio of 1 : 1.
January 2023, AS Unit 3, Q2(b)(ii) (3 marks): Comment on the effect of increasing the concentration of the chemical on the permeability of the membranes to both the pigment and the ions. (3)
January 2023, AS Unit 3, Q2(b)(iii) (5 marks): Devise a method that could be used to obtain the data for the pigment shown in the graph. (5)
January 2023, AS Unit 3, Q2(c) (4 marks): In another investigation, changes in permeability of the membranes were measured over time. The table shows data for the first three hours. Time after addition
October 2022, AS Unit 1, Q1(a)(i) (2 marks): The shapes show the components of a phospholipid. phosphate group glycerol fatty acid covalent bond Draw a diagram to show the structure of a phospholipid, usin
October 2022, AS Unit 1, Q1(a)(ii) (1 mark): Which type of bond is found in this molecule? (1) A ester B glycosidic C hydrogen D peptide
October 2022, AS Unit 1, Q5(a) (1 mark): Name the law on which this formula is based. (1)
October 2022, AS Unit 1, Q5(b) (1 mark): What will happen to the rate of diffusion if all three of the following are changed at the same time? • the surface area is halved • the concentration gradient
October 2022, AS Unit 1, Q5(c) (3 marks): The properties of gas exchange surfaces include: • a large surface area • a short diffusion distance • a high concentration gradient. Describe how mammalian lun
October 2022, AS Unit 1, Q5(d) (6 marks): The photograph shows a hellbender salamander. skin folds (Source: © Robert Hamilton/Alamy Stock Photo) These salamanders live in freshwater streams that are sha
June 2022, AS Unit 1, Q7(a)(i) (2 marks): Draw a diagram of a phospholipid, using the information in the table. (2)
June 2022, AS Unit 1, Q7(a)(ii) (1 mark): One of the bonds present in phospholipids is an ester bond. Which diagram shows an ester bond? (1) H O A N C O O B C C O C C O C H O D N O C
June 2022, AS Unit 1, Q7(b)(i) (2 marks): Explain why an increase in temperature increases the fluidity of the membrane. (2)
June 2022, AS Unit 1, Q7(b)(iii) (2 marks): Explain why a decrease in cholesterol increases the fluidity of the membrane. (2)
June 2022, AS Unit 1, Q7(b)(iv) (1 mark): Suggest why a fatty acid with a shorter side chain will increase the fluidity of a membrane. (1)
June 2022, AS Unit 1, Q7(c)(i) (2 marks): Suggest how the content of the fatty acids in these membranes may have changed. (2)
June 2022, AS Unit 1, Q7(c)(ii) (2 marks): Suggest why these changes are necessary for the survival of the fish. (2)
October 2021, AS Unit 1, Q4(b)(i) (2 marks): The length of the head of a butterfly is 4 mm, the thorax is 6 mm and the abdomen is 18 mm. Estimate the surface area to volume ratio of the butterfly. Assume t
October 2021, AS Unit 2, Q2(a)(i) (2 marks): Calculate the surface area : volume ratio of one cube with a length of 2.5 cm. (2) Answer
October 2021, AS Unit 3, Q2(a)(i) (3 marks): Explain how using a colorimeter allows valid measurements of light transmitted through the betalain solutions. (3)
October 2021, AS Unit 3, Q2(b)(ii) (3 marks): Compare and contrast the effect of these two salts on the loss of betalain from the beetroot cells. (3)
October 2021, AS Unit 3, Q2(b)(iii) (2 marks): Calculate the percentage difference in colour intensity between calcium chloride and ammonium sulfate at a concentration of 0.01 mmol dm−3. (2) Answer %
October 2021, AS Unit 3, Q2(c)(i) (3 marks): Comment on the results shown in the graphs from these two investigations. (3)
October 2021, AS Unit 3, Q2(c)(ii) (3 marks): Explain how you could modify the method to decide if the difference in colour intensity, at a concentration of 0.002 mmol dm−3, is statistically significant. (3
June 2021, AS Unit 1, Q8(a)(i) (1 mark): The magnification of this diagram is 1 × 107. The structure labelled T is 2 units long. What is this unit? (1) A cm B mm C µm D nm
June 2021, AS Unit 1, Q8(a)(ii) (1 mark): Which structures contain a phosphate group? (1) A Q and R B Q and T C R and S D S and T
June 2021, AS Unit 1, Q8(a)(iii) (1 mark): Which ratio of the structures affects the fluidity of this membrane? (1) A Q : T B R : Q C R : T D S : T
January 2021, AS Unit 1, Q5(a) (3 marks): The photograph shows part of a cell membrane, as seen using an electron microscope. cell membrane (Source: © Dennis Kunkel Microscopy / Science Photo Library) T
January 2021, AS Unit 1, Q5(b) (3 marks): Cell membranes contain cholesterol. The molecular formula of cholesterol is C27H46O. The diagram shows a cholesterol molecule. hydrocarbon tail hydrocarbon ring
January 2021, AS Unit 1, Q5(c)(ii) (4 marks): Explain the permeability of cell membranes to each chemical shown in the diagram. (4)
January 2021, AS Unit 1, Q6(a)(ii) (2 marks): Smoking is a cause of emphysema. People with emphysema have weakened alveoli that can collapse, creating fewer but larger alveoli. Explain how this will affect
January 2021, AS Unit 1, Q6(b) (6 marks): Bird embryos develop inside hard-shelled eggs. Gas exchange occurs across the shell of the egg. The oxygen diffuses into the bloodstream of the developing embry
January 2020, AS Unit 3, Q3(b)(ii) (4 marks): Plot a line graph to show the relationship between detergent concentration and percentage of light transmitted. Join the points with straight lines. (4)
January 2020, AS Unit 3, Q3(b)(iii) (3 marks): Detergent permanently damages beetroot cell membranes. Explain what will happen to the rate of loss of betalain if these discs are then transferred to test tube
January 2020, AS Unit 3, Q3(b)(iv) (3 marks): In a second investigation, the effect of temperature on beetroot cell membrane permeability was studied. The graph shows the results of the second investigation
January 2020, AS Unit 3, Q3(b)(v) (3 marks): Estimate the percentage of light transmitted at 80 °C. Use the information in the graph and your own knowledge to support your answer. (3)
January 2019, AS Unit 1, Q5(a)(i) (2 marks): Calculate the volume of this liposome, using the formula V = 4 3 πr3 (2) Answer
January 2019, AS Unit 1, Q5(a)(ii) (2 marks): Explain the arrangement of phospholipids in liposomes. (2)
January 2019, AS Unit 1, Q5(b)(ii) (3 marks): Describe the effects of cholesterol and temperature on membrane permeability, as shown in the graph. (3)
January 2019, AS Unit 1, Q5(b)(iii) (2 marks): Explain why cholesterol and temperature affect membrane permeability. (2)
January 2019, AS Unit 1, Q6(a)(i) (1 mark): Estimate the ratio of phosphatidylserine in the inner layer to that in the outer layer before the blood clotting process is triggered. (1) Answer
January 2019, AS Unit 1, Q6(a)(ii) (2 marks): Describe the effect that the movement of phosphatidylserine into the outer layer will have on the content of phospholipids in the membranes of platelets. (2)
January 2019, AS Unit 1, Q8(a) (2 marks): The height of a mouse is 3 cm. Calculate how many times taller an elephant is than a mouse. Use the white line drawn on the photograph of the elephant to calcul
January 2019, AS Unit 1, Q8(b) (3 marks): The respiratory system of an elephant is different from that of other mammals. The lungs are attached to the chest cavity wall and diaphragm by collagen fibres.

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